Acardia is a rare and serious malformation that occurs exclusively in monizygous twins - twins developing from a single egg. Acardia represents one of the most severe and rare congenital anomalies. It is characterized by the absence of functioning heart. Acardia results from the artery to artery connections in the placenta, thereby causing a physically normal fetus to circulate blood for itself as well as a severely malformed fetus suffering from heart regression. In other words, fetus acardius is a parasite and it receives blood supply from the donor twin. Because the pump twin heart has to pump for two, there is a high risk of going into heart failure and this would lead to the death of the normal twin.
The most common variety is the acardius acephalus where the head is lacking and so are the upper extremities. Other types are acardius anceps, acardius acormus and acardius amorphous. While in acardius anceps, the most highly developed form, a partly developed head with remnants of cranial bones and brain tissue are present with developed body and extremities, acardius acormus is the rarest form of acardia. The monster is a head without a body. Acardia amorphous is the least developed monster not recognizable as a human form, with minimally developed visceral organs. Since there is no gross human form, the name acardius amorphous.
As to the cause of acardia, the etiology of acardiac monster is still unknown. Genetic defects have been reported to be the cause. Some researchers suggest chromosomal abnormalities to be the reason. Krause and Bejdl suggest that compression of the cephalic pole of the embryo prohibiting curving and fusion of the primitive heart tube to be the basic cause of this anomaly. As a result, the dependant entodermal organs like thyroid, esophagus, trachea, lung, liver and others are also not formed.
A pregnant woman carrying an acardiac twin is unlikely to have any unusual symptoms. An acardiac twin is often found incidentally on prenatal ultrasound. As no two acardiac twins are formed exactly alike, they may present differently. Several improved imaging techniques like 2D ultrasonography, 3D ultrasonography and transvaginal Doppler ultrasonography have made diagnosis of acardia possible even in the first trimester of pregnancy. Such early diagnosis helps to reduce the risk of complications. Fetal echocardiography is also recommended to assist in early detection of heart failure in the normal twin. Chromosome studies are also done on both fetuses.
One line of treatment is watching for the earliest signs of heart failure in the pump twin with frequent ultrasounds. If heart failure is identified and the pregnancy is also far enough, then the pump twin should simply be delivered. Physicians recommend prenatal interruption of the blood vessel connections before heart failure develops in the pump twin, thus sacrificing the acardiac twin.
Specialists use laser, electrical cauterization and electrodes, serial amniocentesis, medications and other treatments successfully. If the acardiac twin is large enough and the amount of blood flow to it can cause heart failure in the healthy twin, then blood flow is stopped with Fetal Image-Guided Surgery. The acardiac or parasitic twin never survives, as it is severely malformed and does not have a functioning heart. The normal twin is at risk for heart failure and complications associated with premature birth. The normal twin is expected to have about 10% risk for malformations.
Fetal surgery refers to the surgical treatment of the developing baby in the womb to rectify congenital defects. Surgery of the fetus is performed to fix the prenatally diagnosed anomalies. However fetal surgery is a complicated procedure and comes with lot of risks to both mother and the baby. Yet, doctors recommend fetal surgery, if the risks associated with continuing the pregnancy, without surgical intervention, outweighs the risks that come with fetal surgery. Certain abnormalities, if left to progress in the womb, may turn fatal and infant may die soon after the birth. However fetal intervention is initiated only after taking the safety of the mother into consideration. The common risks that are associated with fetal surgery are premature delivery, infection of the uterus, leaking of amniotic fluid through the membrane, potential infertility and the risk of anesthesia.
There are various techniques followed to diagnose fetal anomalies. The diagnostic method can be non invasive such as ultrasound, fetal echocardiography, MRI, Radiography, Measuring MSAFP (maternal serum alpha-fetoprotein) and Measuring maternal serum beta-human chorionic gonadotropin (HCG) or invasive procedure such as amniocentesis, Chorionic villus sampling and Percutaneous umbilical blood sampling (PUBS) are used to detect the birth defects.
Types of Fetal Surgery
Depending on the incision level, fetal surgery is classified into three types.
Open Fetal Surgery
Open fetal surgery is almost similar to cesarean section and involves a total opening of the uterus. In this type of surgery, a long incision is made in the mother's abdomen and then on the uterus to reach the fetes. Once the surgical correction is performed on the fetus to treat the birth defect, the uterus and abdominal is closed back leaving the fetus intact. Open fetal surgery is performed under general anesthesia. Surgery is performed using special instruments containing staples to prevent bleeding from uterus. During the operation, warm saline water is infused to maintain the position of placenta and umbilical cord and surgeon will keep a vigil on the pulse and heart rate of the baby with the help of the oximeter. After the surgery, the mother is hospitalized for close to a week to facilitate close monitoring. One should remember that, with open fetal surgery, mother will forgo the option of vaginal delivery for the present and future deliveries. She can deliver the baby only through C-section. She may be given some medication to avoid pre term labor. Open fetal surgery is followed for the conditions like chest mass, neck mass, spinbifida, myelomeningocele and Sacrococcygeal teratoma (SCT) (a tumor at the base of the child's tail bone).
There is one more variation to the open fetal surgery called the EXIT (Ex Utero Intrapartum Treatment) Procedure. EXIT surgery is performed at the end of the full term and just before the delivery. In this method the baby is partially delivered by bringing out only a part of the fetes from uterus and keeping rest of the fetes attached to placenta and umbilical cord to allow blood circulation. Once the defect is rectified, the baby is delivered fully. Exit procedure is essentially followed to correct the airway blockage in the baby.
Fetoscopic surgery is minimally invasive and unlike open fetal surgery, fetes remains inside the uterus while operating. Surgeon uses special instruments such as laser and makes a small incision with the help of the fetoscope to correct the birth defects. Fetoscopic surgery has shown high success rate in conditions such as Twin-Twin Transfusion Syndrome (TTTS), Twin Reversed Arterial Perfusion (TRAP), Amniotic band syndrome, and Tracheal occlusion for CDH. Fetoscopic surgery does not pose a risk of pre term labor and also eliminates most of the risks associated with open fetal surgery. This is essentially why fetoscopic surgery is the preferred choice, yet one should note that few complicated birth defects can be corrected only through open fetal surgery.
Fetal image guided surgery
Fetal image guided surgery is the least invasive of all wherein surgery is performed with the guidance of images of fetus produced on the external screen by ultrasound. Very thin instruments are inserted through a small opening in the abdomen and the correction is made without any endoscopic view and the whole procedure is guided by the sonogram images.
Various congenital conditions treated through fetal intervention
Congenital diaphragmatic hernia (CDH): Congenital diaphragmatic hernia (CDH) refers to the opening in the diaphragm through which the contents of the abdomen enter the chest cavity leaving no space for the lungs to develop properly. This is a serious condition and may lead to respiratory failure after birth. This condition, depending upon its severity, is treated through fetal intervention.
Spina bifida: Spina bifida refers to a condition wherein spinal column of the baby does not close properly around the spinal cord and the nerves start to protrude through the opening. Spina bifida can range from mild to severe form, and the severe cases lead to serious neurological problems after the birth. Only the severe form of spina bifida like Meningocele and Myelomeningocele call for fetal intervention through open fetal surgery.
Neck masses: Neck masses are the tumors of the neck that may obstruct the airway and esophagus of the child and also increase the level of amniotic fluid surrounding the baby. Typically, tumors of any kind are treated after birth. In rare cases they grow very large and may even cause heart failure. In such cases fetal intervention becomes necessary to remove the tumors.
Lung lesions: Lung lesions refer to the abnormal growth of lung tissue and these lesions can be cystic (fluid filled) or solid. There are various types of lung lesions and treatment depends upon their size and location. During pregnancy, continuous monitoring is necessary to keep vigil on the size of the lesion. Most often lung lesions shrink and make way for normal development. Lesions of smaller and moderate size are best treated after delivery. But if the size of the lung tumor is abnormally huge and poses a risk of hydrops (excess accumulation of fluid in the fetus) fetal intervention is initiated. Cystic lesions are normally removed through needle aspiration under the constant guidance of ultrasound images, but solid lesions require more elaborate procedure such as EXIT.
Congenital heart diseases: Not all congenital heart defects call for fetal intervention. Sometimes the septum (wall separating the right and left side of the heart) of the heart develops a hole while in the womb. However septum defects are typically treated after the birth of the child and rarely require fetal surgery. But if the heart develops severe obstructive cardiac disorders such as aortic stenosis, pulmonary stenosis and coarctation of the aorta,a fetal image-guided procedure may be necessary to open or enlarge the narrowed valve. This procedure involves placing a balloon catheter by inserting it through the uterus and into the fetal’s heart.
Amniotic Band Syndrome: This is a condition where fetus is entrapped in fibrous amniotic bands in the womb, restricting blood flow to the affected portion of the fetes. It normally affects legs, arms, toes and fingers. In utero surgery may be performed to rectify the condition if there is risk of amputation of the limb after the birth.
Twin-to-twin transfusion syndrome (TTTS): TTTS is a condition that occurs in identical twins wherein unbalanced exchange of blood takes place between the twins. One receives higher amount of blood whereas the other receives less amount. The fetus with less blood supply may become anemic and the one with excess blood supply may suffer heart failure due to excess fluid. Fetal surgery through laser fetal intervention is the preferred option to correct the condition. This procedure involves inserting a laser along with small telescope into the uterus and separating the blood vessels on the placenta that are connected to both twins.
Congenital high airway obstruction syndrome (CHAOS): Congenital high airway obstruction syndrome (CHAOS) refers to the blocking of fetal airway resulting in enlarged lungs, windpipe and bronchial tube. A complete or near to complete blockage may lead to a heart failure. Though congenital high airway obstruction syndrome (CHAOS) is treated after birth, in severe cases where fetes is at high risk such as hydrops, fetal surgery is performed.
Obsessive compulsive disorder
The exact cause of obsessive compulsive behavior is yet to be established. On the basis of some studies and research carried so far, possible causes include any one or a combination of two.
Genetics (family history): Multiple genes passed on through generations are likely to affect the sufferer whose close relative is diagnosed with OCD as well. The genetic connection proves to be higher if the onset of OCD is before age 14. Identical twins have a 70% chance of sharing the disorder.
Illness: If the person is suffering from other anxiety disorder like depression, , substance abuse disorder, a personality disorder, attention deficit disorder, he or she is most likely to experience a high level of anxiety. Certain auto immune diseases such as Sydenham's chorea, rheumatic fever, pediatric streptococcal infection may also cause obsessive compulsive disorder.
Serotonin Hypothesis: People diagnosed with OCD are believed to have abnormally low levels of brain chemical, the serotonin which helps carry messages from one nerve cell to another. This imbalance may interfere with the normal biological processes including mood, sleep, appetite, impulse control, aggression and pain.
Structural brain differences: Abnormalities in several parts of the brains including the thalamus, caudate nucleus, orbital cortex and cingulated gyrus may also be a cause for OCD.
The disorder is clearly visible right from early childhood. Check for one or more of the following traits which are generally associated with time, dirt, relationship and money. Unless and until the individual has trouble leading a normal life due to any or all of these traits, it is not diagnosed as a disorder.
If left unattended, OCD can have devastating effects both in personal life and at the workplace. Normal life can be completely marred. Most importantly, individuals with OCD are close to acknowledging the need for help as compared to those affected with OCPD who do not conceive it as a problem, hence do not seek help until or unless someone forces the issue.
Antidepressant medications and behavior therapy are effectively used in treating OCD. Medication other than certain antidepressants is rarely prescribed. Instead individual psychotherapy or counseling helps treat OCPD. With family support and an empathetic attitude by those in contact, improvement is evident within few weeks of professional assistance.
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Bibliography / Reference
Collection of Pages - Last revised Date: September 20, 2020